Posts Tagged ‘Buderus’

The second disadvantage of most Direct Vent Condensing Boilers is their restrictive heat exchangers. Not all DVCB have this disadvantage however so you must make sure to ask your contractor about this. Let’s say that you have a 3,000 square foot home with an 80,000 BTUH boiler. You would probably need about 8-10 GPM or 8-10 gallons of water passing through your boiler per minute. Most boilers would have a pressure drop through your boiler of 8 feet of head. The best boilers have a pressure drop as low as 5 feet of head. This means that with the right boiler your pump will work half as hard. Pumping water around your house uses quite a bit of electricity. With a non restrictive heat exchanger, you will be able to keep this cost to a minimum.

Make sure that your contractor understands pump and boiler flow curves so that your system will be designed to run as efficiently as possible.

Hi Again, Turndown is the ability of a boiler to reduce its input to match the load. Imagine a home with 3 floors and a separate thermostat and heating zone for each floor. When all three floors require heat, the demand might be 80,000 BTUH. This would require an 80,000 BTUH boiler. If only the basement needed heat, the load might only be 20,000 BTUH. Firing an 80,000 BTUH boiler would be overkill and horribly inefficient. All DVCB have a turndown that allows the boiler to fire at the required rate for that time so the boiler would fire just at the 20,000BTUH that you need. Efficiency is enhanced once again.

Now that it is crystal clear that the best option for a boiler is the DVCB, Direct Vent Condensing Boiler, I would like to discuss the problems with these boilers and how to avoid them.

Your thermostat is set for 70 deg. F. The temperature drops to 69 degrees and the boiler fires up. Based on the outside temperature of 50 degrees, your boiler reset controller determines that a water temperature of 100 degrees will provide the right amount of heat. The boiler starts heating your water until it reaches 100 degrees. Your home heats up to 70 degrees and the boiler shuts off, but the temperature doesn’t go up higher because your radiators are only 100 degrees. In order to maintain 70 degrees in your home, tha radiators must stay at 100 degrees so they will never cool down. Rather, they will stay at 100 degrees and maintain your exact set point of 70 degrees in your home. How efficient, How comfortable? As it gets colder outside, your boiler will automatically adjust the water in your system hotter and hotter to meet your exact heating needs. Imagine how comfortable it will feel in your home without temperature fluctuations? Imagine how quiet your system will be without the constant noise of your pipes expanding and contracting as they heat up and cool down. But most of all, imagine how much energy you will save due to this operating efficiency.

Let’s say you have a typical 3,000 square foot home with cast iron baseboard or radiators. This is what happens in a typical heating cycle.
Your thermostat is set at 70 Degrees Fahrenheit. The temperature in your home drops to 69 Deg. F. and your thermostat sends a signal to your boiler to fire. Your entire piping and radiator system is at room temperature or 69 Deg. F. Keep in mind that the weight of all your piping and radiators is around 5,000 lbs. Your boiler fires and starts warming the water, all the steel piping and cast iron radiators to 140 Deg. F. This will take around 20 minutes to achieve since there is 5,000 lbs to heat up. While your house waits for heat, the temperature continues to drop. By the time tha radiators warm up enough to start warming your home, the temperature probably has dropped to 65 Deg. F.
Now your 5,000 lbs of steel and cast iron has reached 140 degrees and the temperature has reached setpoint at 70 degrees. The boiler shuts off but the 5,000 lbs of steel in your home is still radiating het and the temperature in your home continues to rise. By the time your heat peaks and the radiators cool down and stop emitting heat, your home is probably 75 degrees.
Now your house starts to cool and the cycle starts all over again.
What is happening is that yu are getting a very wide range on 10 degrees in your home. This will not be comfortable and as you het your home to 75, you are wasting loads of energy.

In my next post I will illustrate the heating cycle with a DVCB (Direct Vent Condensing Boiler) that is equipped with Outdoor Reset.

Today we will discuss RESET. Reset is the ability of a boiler to change the water temperature in your radiators to meet your specific heating needs in real-time as the outdoor temperature changes. A standard boiler will typically keep your radiators at 140 degrees Fahrenheit. On really cold days, this is great. For milder days however, your radiators don’t need to be so warm. When it is just a bit cool outside, 90 degree Fahrenheit radiators would be enough. As it gets colder outside, your radiators would need to warm up to keep your house warm. A boiler with the Outdoor Reset feature will constantly measure the temperature outside and adjust your water temperature to give you just the right amount of heat. Now that’s what I call efficient.
In my next post I will illustrate the typical heating cycle without outdoor reset.

The following video is a great simulation of what happens in my favourite DVCB, the Triangle Tube Prestige during a heating cycle. Check it out!

One of the great operational advantages available with a Mod/Con (Modulating Condensing) boiler is its ability to modulate its heating power to match the requirements of your home. When your boiler is sized, it is designed to provide you with enough heat to keep your home nice and comfortable even on the coldest day of the year. However, most of the time your boiler fires, it is not quite as cold as it was designed for. As a matter of fact, the coldest temperatures only happen less than 3% of the time. All other times, your boiler is too big for your home. When your boiler is too big, it will run in short bursts called “short cycling” and will waste energy. See this video about oversized boilers.

The modulating boiler, however can adjust its heating power to match the actual requirements at the time. This is done in real-time adjusting the boiler’s power depending on weather conditions. Now your boiler is always just the prefect size for your home and is always operating at peak efficiency.

The energy savings of a condensing boiler is compounded by its operating efficiency. Operating efficiency means that the boiler operates in such a way to maximize savings and reduce energy consumption due to this special sequence of operation. This is all in addition to the fact that its combustion efficiency is high. There a several ways in which the modulating condensing boilers offer operational efficiency and depending on which boiler you select, you will benefit from some or all of these operational advantages.

Modulation.

Reset

Low water temperature operation.

Turndown to support zoning.

In my next few posts, I will elaborate on these operational efficiencies and explain them in detail. Please feel free to ask a question if you require additional information.

Combustion Efficiency is the percentage of heat you get from your fuel. For instance, if your boiler has a combustion efficiency of 70%, you are getting 70 cents of heat for every dollar of gas that you are paying for. The rest of the heat is going right up the chimney. This is why you can burn your hand when you touch the hot chimney of a 70% efficient appliance. You are feeling the heat that is being wasted right up the chimney.

If you think about it, you are getting burnt even if you don’t touch the chimney because you are losing/wasting so much energy.

Compare this to a DVCB which has a 95% combustion efficiency and you will see that you are getting 95 cents for every dollar in fuel used. This is a great savings of almost 30%. If you feel the vent of a condensing appliance, it is just a bit warm because you are extracting 95% of the heat from the flu gases before you send them out the vent.

With today’s high energy prices and our concern for the environment, it is a crime not to invest in a DVCB.

The reason for this is that the combustion process is completely isolated from the airstream of your home. All of the combustion air is drawn through a sealed pipe from outside and all of the products of combustion are vented directly to the outside in a sealed pipe. No matter what happens in the combustion process and no matter if the flame is producing CO (Carbon Monoxide), everything will be vented outside with no danger of anything entering your home. This is the best protection that you can provide for your family. The Direct Vent boiler is also the preferred boiler by the TSSA for this very reason. You can see this preference clearly in the language of their bulletin on replacing boilers.
Please see the advisory below.